Power supply regulator

ABSTRACT

This disclosure relates to a snowmobile lighting system having a permanent magnet alternator with a preselected open circuit voltage connected to energize a pair of taillights and a dual filament headlight. A silicon controlled rectifier is connected across the alternator output. A resistance bridge network is also connected across the output of the alternator with one leg of the bridge type network including the taillights. A transistor has its input elements connected across the output terminals of the network and its output elements connected to the gate circuit of the controlled rectifier. The resistance of the taillights increases with the output of the alternator and when it rises about a selected level, the transistor conducts and fires the controlled rectifier. A cutoff switch is connected in parallel with the resistor of the bridge connected to the taillights to directly connect the taillights across the alternator to minimize the output of the alternator. A multiple position switch selectively connects either or both of the filaments of the headlight for bright, dim, or minimal energization, respectively.

atent [1 1 [451 Sept. 4, 1973 POWER SUPPLY REGULATOR [76] Inventor:Floyd M. Minks, Rt. 1, Box 41,

Kissimmee, Fla.

22 Filed: Nov. 16, 1971 21 Appl.No.: 199,388

Related US. Application Data [63] Continuation of Ser. No. 817,787,April 21, 1969,

Primary Examiner-J. D. Miller Assistant Examiner-H. l-luberfeldAttorney-Rives & Rives and Shapiro & Shapiro I [57] ABSTRACT Thisdisclosure relates to a snowmobile lighting system having a permanentmagnet alternator with a preselected open circuit voltage connected toenergize a pair of taillights and a dual filament headlight. A siliconcontrolled rectifier is connected across the alternator output. Aresistance bridge network is also connected across the output of thealternator with one leg of the bridge type network including thetaillights. A transistor has its input elements connected across theoutput terminals of the network and its output elements connected to thegate circuit of the controlled rectifier. The resistance of thetaillights increases with the output of the alternator and when it risesabout a selected level, the transistor conducts and fires the controlledrectifier. A cutoff switch is connected in parallel with the resistor ofthe bridge connected to the taillights to directly connect thetaillights across the alternator to minimize the output of thealternator. A multiple position switch selectively connects either orboth of the filaments of the headlight for bright, dim, or minimalenergization, respectively.

16 Claims, 3 Drawing Figures INTERNAL COMBUSTION ENGINE PATENTEDSEP 4M8INVENTOR. FLOYD M MINKS Attorneys MZTUZM v 1 rowan SUPPLY REGULATOR Thisis a continuation of application Ser. No. 817,787, filed Apr. 21, 1969now abandoned.

This invention relates to an alternator power supply regulator andparticularly to a lighting system having an alternator with apreselected output connected to energize a lighting means.

Motor vehicles are generally provided with headlights and taillights ofthe incandescent variety having filaments mounted in a seal glass shell.In certain vehicles, such as motorcycles and snowmobiles and the like,the lights are connected directly to the output of an alternator whichis driven from the internalcombustion engine. A permanent magnetalternator provides an inexpensive and satisfactory commercialconstruction. Generally, however, the output of such alternators varieswith the engine speed and thus the effectiveness of the lighting varieswith the speed and does not provide a constant illuminating level. Ifthe alternator is constructed to provide suitable illumination level atlow speeds, the increased output at high speeds results in excessiveillumination. Further, the incandescent type light is extremelysensitive to the operating voltage and operation above the rated voltagemay result in rapid deterioration of the lighting components and undercertain conditons may destroy them. Conversely, if the properillumination level is provided at high speeds, the illumination isgenerally inadequate at low speeds.

The present invention is particularly directed to a simple andinexpensive regulator connected across the output of the alternator andresponsive to the energization of the lighting means to maintain arelatively constant illumination level.

Generally, in accordance with the present invention, the lighting meanshave filaments which establish an impedance related to the energizationlevel thereof and constitutes a power sensitive impedance means. Thelighting means is connected as a part of a voltage dividing networkconnected across the output of the altemator. This results in a voltagesignal which is a function of the energization of the lighting means andtherefore the illumination level. This voltage signal is applied tocontrol a triggered switch means such as a solid state electronic switchmeans connected directly across the output of the alternator. Thealternator is a permanent magnet type or the like having a preselectedshort circuit current with the output dropping essentially to zero inresponse to short circuiting of the alternator or to a low impedancepath across the alternator. The voltage dividing network is connected toselectively fire the triggered switch means when the RMS (root meanssquare) value of the voltage output of the alternator rises above thenormal energizing level of the lighting means and thus maintains arelatively constant level of energization.

In a particularly novel and reliable system, a controlled rectifier orthe like is connected as the triggered switch means. A bridge-typeresistance network is connected across the output of the alternator withone leg of the bridge-type network including the taillights. Anamplifying means, such as a transistor, has its input elements connectedacross the output terminals of the network and its output elementsconnected in the gate firing circuit of the controlled rectifier. In theoperation, the resistance of the leg of the bridge including thetaillights increases with the RMS value of the output of the alternatorand also with the lighting of the taillights and thus defines the powersensitive impedance means. If the voltage should rise above the normalenergizing level, the transistor is biased on and provides a firingsignal to the controlled rectifier to thereby remove the output. Thethermal time constant of the taillights is substantially greater thanthe period of the alternator. The taillights thus provide a powersensitive impedance means with an effective averaging or in someinstances phase type control.

Although the circuit regulator may not always provide a highly accuratephase control of the alternator output, it has been found to provide asufficient control to maintain a relatively constant energization of thetaillights and the headlight. If it is desired to turn off theenergization of the lighting means, a cutoff switch may be provided inthe network to connect the taillights or to by-pass a portion of thenetwork and directly connect the taillights across the alternator. Thisprovides a continuous signal to the transistor for a relativelyinsignificant output of the alternator and maintains a gate signal onthe control rectifier such that the output of the alternator isessentially held at zero.

In motorcycles, snowmobiles and similar circuits, it is often desirableto maintain continuous energization of the headlights during both nightand day operation. The energizing of the filaments prevents damage as aresult of vibration and the like. The energization during the day periodcan, however, be substantially reduced over the illumination requiredfor nighttime use. A multiple switching may be provided to selectivelyconnect the filaments of the headlight for the normal, bright and dimenergization. Additionally, in accordance with the present invention,the several filaments of the headlight may be selectively connected inseries or in parallel across the output of the alternator to provide thedesired daytime illumination level.

The present invention has been found to provide a reliable andinexpensive voltage light regulator for alternator driven lightingsystems.

The drawing furnished herewith illustrates the best mode presentlycontemplated by the inventor for carrying out the invention anddisclosed the above advantages and features as well as others which willbe readily understood from the following description.

In the drawing:

FIG. 1 is a schematic circuit diagram of a light regulator constructedin accordance with the present invention and forming a part of alighting system suitable for a snowmobile, motorcycle and the like;

FIG. 2 is a schematic circuit diagram showing an alternative headlightconnection for the lighting system shown in FIG. 1; and

FIG. 3 is a similar schematic circuit diagram of further alternativecircuit connection.

Referring to the drawing and particularly to FIG. 1, the presentinvention is shown applied to an alternator supplied lighting system fora motorcycle, snowmobile or other device having a headlight l and a pairof taillights 2 and 3. An internal-combustion engine 4 is connected todrive an alternator 5 which in turn is interconnected to energize theheadlight l and to the taillights 2 and 3.

The alternator 5 is preferably of a permanent magnet type for practicalcommercial reasons and the output is thus dependent upon the speed ofthe intemalcombustion engine 4.

The energization level of the headlight l and the taillights 2 and 3 iscontrolled in accordance with the present invention to provide arelatively constant level of illumination by the headlight 1.

More particularly in the illustrated embodiment of the invention, theheadlight 1 is shown as a dual element unit, such as presently widelyemployed in motorcycles and snowmobiles. Generally, the headlight 1includes a high beam filament 7 and a low beam filament 8. The filaments7 and 8 are series-connected across the alternator output lines 9 and 10in FIG. 1. The junction of the filaments 7 and 8 provides a center tap11 which is interconnected to the contact arm 12 of a three-positionswitch unit 13 for selective connection of the filaments 7 and 8 tolines 9 and 10.

The switch unit 13 includes a centrally located dead contact 14. Whenthe contact 12 is positioned in engagement with dead contact 14, thefilaments 7 and 8 are connected in series across the lines 9 and 10.This will maintain a low level energization of both filaments andconsequently provide a minimal output. This maintains satisfactoryenergization of the headlight to prevent damage reslting from vibrationand the like during the operation of the vehicle. The three-positionswitch unit 13 includes a low beam filament contact 15 connected to theline 9. When the switch arm 12 engages the contact 15, the high beamfilament 7 is by-passed and only the filament 8 is connected across thelines 9 and 10. This provides the desired low beam illumination.

The three positioned switch 13 further includes a high beam filamentcontact 16 shown disposed to the opposite side of the dead contact 14and interconnected directly to the line 10. When the contact arm 12 ispositioned to engage the-contact 15, only the filament 7 is connectedacross the lines 9 and 10.

As previously noted, the energization of the headlight 1 is regulated bythe special RMS regulator 6 which incorporates the taillights 2 and 3 toestablish energization of the headlight l at an essentially constantlevel.

In the illustrated embodiment of the invention, the taillights 2 and 3are connected in parallel with each other and define one leg of aresistance bridge network having input terminals a and b connected tothe alternator 5 and output or signal terminals 0 and d. The filaments17 and 18 of the taillights 2 and 3 are connected in parallel with eachother and in series with a resistor 19 between the alternator outputlines 9 and 10. The filaments 17 and 18 have an impedance related to theenergization current level of the filaments and consti tute powersensitive impedance elements providing a signal in accordance with theroot mean square of the voltage applied by the alternator to theheadlight. As the alternator voltage drops applied across the circuitincreases, the temperature of the filaments increases and resistance orimpedance of the filaments correspondingly increases. The voltage at thejunction of the resistor 19 and the parallel filaments 17 and 18provides a preselected voltage at the desired output of the alternator.For example, the resistor 19 may be selected to have essentially thesame voltage as the para]- leled filaments at the desired operatingvoltage.

A pair of balancing resistors 21) and 21 are connected in series witheach other between the alternator output lines 9 and 10. The centerconnection of the resistors 20 and 21 provides a second voltage pointrelated to the output of the alternator 5.

In the illustrated embodiment of the inventin, an amplifying device isconnected across the output of the bridge network. The amplifying deviceis shown as a PNP transistor 22 having the emitter 23 connected to thejunction of the resistor 19 and the paralleled filaments 17 and 18. Thebase 24 of transistor 22 is connected to the junction of theseries-connected resistors 20 and 21. The collector 25 of transistor 22is connected to control a triggered switch means 26. When the voltageacross the filaments 17 and 18 increases to a selected percentage of thealternator output voltage, the transistor 22 is biased on and conductsto energize the switch means 26.

The switch means 26 is shown invention, a silicon controlled rectifier26 having its anode-to-cathode elements connected directly across theoutput of the alternator 5. When the rectifier 26 conducts, a very lowimpedance path, which is essentially a short circuit, appears across theoutput of the alternator 5. ln accordance with known theory, the outputof the alternator 5 will, therefore, drop to essentially zero for theperiod of conduction of the rectifier 26. This period of conduction willextend in time past what would be the next polarity reversal of thealternator output. This is caused by the fact that the output impedanceof the alternator is primarily inductive. Thus, even though the siliconcontrolled rectifier controls only one polarity of the output, it canreduce the RMS output well below 50 percent of its normal value. Theperiodic firing of the controlled rectifier 26 therefore holds theaverage output of the alternator 5 at a relatively constant level.

Although a highly accurate phase control may not be established,applicant has found that the regulation is highly satisfactory forpurposes of controlling the energization of vehicle headlights. A singletail lamp could, of course, be used, or one of the tail lampssubstituted for resistor 20. Using tail lamps for two bridge legs wouldgive greater bridge output but would also cornplicate wiring.

In the illustrated embodiment of the invention, a resistor 27 in serieswith a diode 28 is connected between the collector 25 of transistor 22and the gate 29 of the controlled rectifier 26. The anode30 of therectifier 26 is connected to the line 9 and the cathode 31 is connectedto the line 10. Thus, whenever line 9 is positive with respect toline10, the rectifier 26 is biased in the direction to conduct.correspondingly, the voltage dividing network can apply a turn-on signalto the gate 29 during this half cycle if the voltage level sensed by thetaillight filaments l7 and 18 indicates an excessive output voltage.

A stabilizing resistor 32 and a paralleled transient by-. pass capacitor33 may be connected across the gate to cathode circuit of the recitifer26, as illustrated in FIG. 1.

A capacitor 34 may be connected across the alternator 5 and a capacitor35 may be connected across the filaments l7 and 18 of the taillights 2and 3. Capacitors 34 and 35 are selected to by-pass ignition noise andthe like from the circuit and thus contribute to stable operation.

The operation of the illustrated embodiment is summarized as follows. Ifthe RMS output of alternator 5 rises above a desired level, the voltageappearing across the taillight filaments 17 and 18 increases with acorresponding increased impedance. The voltage applied to the emitter 23of the transistor 22 therefore increases with respect to the voltageapplied to the base 24. During the period that the alternator outputline 9 is positive relative to line 10, the voltage applied to theemitter 23 biases the transistor 22 to conduct. At a selected level, thetransistor will conduct and completes the circuit from the line 9through the resistor 19, the emitter to collector path of the transistor22, the current limiting transistor 27 and the diode 28, and the gate 29to cathode 31 of the controlled rectifier 26, back to the opposite line10. The controlled rectifier 26 will therefore conduct and establish alow impedance circuit across the alternator 5. This reduces the outputof the alternator 5 and essentially removes the voltage from theheadlight'l and the taillights 2 and 3. The thermal time constant of thetaillights 2 and 3 is generally, for commercially available lights,substantially greater than the period of the alternator 5 such that theresistance of the taillight filaments l7 and 18 will not changeinstantaneously with the changes in the applied voltage, but rather to avery substantial number of complete output cycles of the alternator 5.The filaments l7 and 18 respond sufficiently rapidly to prevent anynoticeable visual change in the output of the headlight l and thetaillights 2 and 3.

Under all three positions of the switch unit 13, the energizationvoltage of the headlight l is maintained at a selected maximum level.

If it is desired to essentially turn off the lighting circuit, a switchmeans may be provided to reduce and hold the output of the alternator 5essentially at zero; for example, as shown in FIG. 2.

In FIG. 2, a switch 36 is connected directly in parallel with theresistor 19 to connect the top side of the paralleled filaments and theemitter 23 of transistor 22 directly to line 9. Whenever the alternator5 goes slightly positive at line 9, the transistor 22 is biased toconduct and fires or triggers the controlled rectifier 26 to establishthe short circuit across the alternator 5 for the corresponding polarityportion of the cycle. This, in turn, will essentially maintain theoutput of the alternator 5 very near zero. Although the oppositepolarity portion of the cycle remains, its duration is reduced belowonehalf the normal period and the energization level is minimal.Further, if considered necessary to remove the opposite half cycle, abi-lateral controlled rectifier, such as a Triac" or a pair ofback-to-back controlled rectifiers may be provided with appropriatefiring means to clip both half cycles in response to the closing ofswitch 36 and/or the output of the bridge structure or the like.

In FIG. 3, a further modification to the circuit of FIG. 1 is shownwherein the output voltage is reduced with the switch in the of positionby parallel connection of the headlight filaments to the alternatoroutput lines 9 and 10. Only the portion of the circuit including themodified interconnection of the headlight filaments is therefore shownin FIG. 3, and corresponding elements in FIGS. 1 and 3 are similarlynumbered for purposes of simplicity and clarity of explanation. Theheadlight 1 includes the high beam filament and low beam filamentinterconnected in series with the center tap connected directly to theline 9. The opposite ends of the filaments 7 and 8 are connected to linethrough a double pole, double throw, switch unit 37 having a pair ofcontact arms 38 and 39. The contact arm 38 is shown connected to theouter end of the high beam filament 7 and is selectively engageable withany one of three contacts 40, 41 and 42 which are shown in verticalalignment in FIG. 3. The adjacent upper contact 40 and intermediatecontact 41 are interconnected directly to line 10. The lower contact 42is a dead contact and provides an open circuit connection to thefilament. Thus, whenever the contact arm 38 engages either contact 40 or41, the filament 7 is connected across the alternator output lines 9 and10.

The associated contact arm 39 similarly selectively engages any one ofthree contacts 43, 44 and 45. The lower contact 43 and the intermediatecontact 44 are both connected to the line 10. The upper contact 45constitutes the dead contact.

With the switch unit 37 positioned to hold the contact arms 38 and 39 inan intermediate position engaging respectively contacts 41 and 44, thefilaments 7 and 8 are connected in parallel with each other between thelines 9 and 10. The resistance of the paralleled filaments 7 and 8 isless than the series resistance and the circuit of FIG. 3, therefore,provides a reduction in the output voltage of the alternator 5 and acorresponding reduction in the illumination.

If the switch unit 37 is moved upwardly, the contact arm 38 engagescontact 40 to maintain connection of the filament 7 across the lines 9and 10. However, the

- contact 39 simultaneously moves into engagement with the dead contact45 and thus removes the filament 8 from the circuit. Conversely,movement of the contact arms 38 and 39 in the opposite or downwarddirection in FIG. 3 removes the filament 7 while maintaining the circuitconnection to the filament 8.

The switch 37 of FIG. 3 permits selective interconnection of eitherfilaments 7 and 8 into the circuit for controlled illumination and inthe off position, connects the filaments 7 and 8 in parallel to minimizethe alternator output and illumination level. The circuit otherwiseoperates in the same manner as that described with respect to FIG. 1.

g The parallel, circuit connection of FIG. 3, in combination with thecutoff switch of FIG. 2, reduces the output voltage in the greatestdegree.

Although the illustrated embodiments of the invention include unilateralcontrolled rectifiers, the present invention includes bi-lateraldevices, such as Triac" units or unilateral rectifiers connected toconduct during the alternate half cycles in combination with appropriategating means to thereby clip such alternate half cycles and provide aregulated output.

The present invention provides a relatively simple and inexpensive RMSvoltage regulator for maintaining a relatively constant illuminationlevel.

I claim:

1. A system for regulating the AC power supplied by a source to lightingmeans, comprising means for varying the flow of AC power from saidsource to said lighting means, means including a power sensitiveimpedance having a characteristic which varies with the root mean squarevoltage applied therein for producing a signal dependent upon the rootmean square voltage applied by said source to said lighting meansirrespective of substantial variations of frequency, amplitude, waveformand symmetry of the AC power supplied, and means responsive to saidsignal for controlling said power-flow-varying means to regulate thepower supplied to said lighting means.

2. A system in accordance with claim 1 wherein said impedance comprisesan incandescent lamp.

3. A system in accordance with claim 2 wherein said lamp is connected inseries with resistor means.

4. A system in accordance with claim 1, wherein said power-flow-varyingmeans is a gate-controlled semiconductor switch connected across saidsource and having the gate thereof responsive to said signal.

5. A system in accordance with claim 4, wherein said signal-responsivemeans includes means for turning on said semiconductor switch for aportion only of the AC cycle of said source.

6. A system in accordance with claim 4, wherein said semiconductorswitch is connected directly across siad source.

7. A system in accordance with claim 1, wherein said signal-responsivemeans includes means for controlling said power-flow-varying'means tolimit the power flow to said lighting means when the root mean squarevoltage applied to said lighting means reaches a predetermined level.

8. A system in accordance with claim 1, wherein said source is analternator.

9. A system in accordance with claim 8, wherein said alternator is apermanent magnet type.

10. A system in accordance with claim 1, wherein said power sensitiveimpedance has a time constant long relative to theperiod of the ACsource and is substantially insensitive to source voltage variations ofrelatively short duration.

11. A system in accordance with claim 1, wherein said signal-producingmeans comprises a bridge circuit having said power sensitive impedancein one leg thereof, said bridge circuit having an input connected acrosssaid lighting means and having an output at which said signal isproduced.

12. A system in accordance with claim 11, further comprising means foramplifying the signal at the output of said bridge circuit and forcoupling an amplified signal to said poWer-flow-varying means.

13. A system in accordance with claim 1, wherein said lighting meanscomprises incandescent lamp means for illuminating night time movementof a vehicle, and means separate from said power sensitive impedanceconnected to said source for reducing the illumination level of saidlamp to a day time level substantially below the illumination level fornight time and sufficient to prevent vibration damage of said lampmeans.

14. A system in accordance with claim 1, wherein said signal producingmeans has connecting means for applying to said signal producing means avoltage which is substantially in accord with the voltage applied tosaid lighting means by said source.

15. A system in accordance with claim 1, wherein the power-flow-varyingmeans is controlled by said controlling means to regulate the powersupplied to said lighting means on alternate half-cycles only.

16. A system for regulating the power supplied by a source to a load,comprising a gate-controlled semiconductor switch connected across saidsource, a bridge circuit having an input connected across said load andincluding a power sensitive impedance in one of the legs thereof forproducing a signal at an output of said bridge circuit dependent uponthe root mean square voltage applied by said source to the load, andamplifier means coupling said signal to the gate of said switch forturning on said switch when the signal reaches a predetermined level.

1. A system for regulating the AC power supplied by a source to lightingmeans, comprising means for varying the flow of AC power from saidsource to said lighting means, means including a power sensitiveimpedance having a characteristic which varies with the root mean squarevoltage applied therein for producing a signal dependent upon the rootmean square voltage applied by said source to said lighting meansirrespective of substantial variations of frequency, amplitude, waveformand symmetry of the AC power supplied, and means responsive to saidsignal for controlling said power-flow-varying means to regulate thepower supplied to said lighting means.
 2. A system in accordance withclaim 1 wherein said impedance comprises an incandescent lamp.
 3. Asystem in accordance with claim 2 wherein said lamp is connected inseries with resistor means.
 4. A system in accordance with claim 1,wherein said power-flow-varying means is a gate-controlled semiconductorswitch connected across said source and having the gate thereofresponsive to said signal.
 5. A system in accordance with claim 4,wherein said signal-responsive means includes means for turning on saidsemiconductor switch for a portion only of the AC cycle of said source.6. A system in accordance with claim 4, wherein said semiconductorswitch is connected directly across siad source.
 7. A system inaccordance with claim 1, wherein said signal-responsive means includesmeans for controlling said power-flow-varying means to limit the powerflow to said lighting means when the root mean square voltage applied tosaid lighting means reaches a predetermined level.
 8. A system inaccordance with claim 1, wherein said source is an alternator.
 9. Asystem in accordance with claim 8, wherein said alternator is apermanent magnet type.
 10. A system in accordance with claim 1, whereinsaid power sensitive impedance has a time constant long relative to theperiod of the AC source and is substanTially insensitive to sourcevoltage variations of relatively short duration.
 11. A system inaccordance with claim 1, wherein said signal-producing means comprises abridge circuit having said power sensitive impedance in one leg thereof,said bridge circuit having an input connected across said lighting meansand having an output at which said signal is produced.
 12. A system inaccordance with claim 11, further comprising means for amplifying thesignal at the output of said bridge circuit and for coupling anamplified signal to said power-flow-varying means.
 13. A system inaccordance with claim 1, wherein said lighting means comprisesincandescent lamp means for illuminating night time movement of avehicle, and means separate from said power sensitive impedanceconnected to said source for reducing the illumination level of saidlamp to a day time level substantially below the illumination level fornight time and sufficient to prevent vibration damage of said lampmeans.
 14. A system in accordance with claim 1, wherein said signalproducing means has connecting means for applying to said signalproducing means a voltage which is substantially in accord with thevoltage applied to said lighting means by said source.
 15. A system inaccordance with claim 1, wherein the power-flow-varying means iscontrolled by said controlling means to regulate the power supplied tosaid lighting means on alternate half-cycles only.
 16. A system forregulating the power supplied by a source to a load, comprising agate-controlled semiconductor switch connected across said source, abridge circuit having an input connected across said load and includinga power sensitive impedance in one of the legs thereof for producing asignal at an output of said bridge circuit dependent upon the root meansquare voltage applied by said source to the load, and amplifier meanscoupling said signal to the gate of said switch for turning on saidswitch when the signal reaches a predetermined level.